Specimen drying apparatus

ABSTRACT

For quantitative determination of water in a specimen of known weight, the specimen is supported in an oven in a manner that air can circulate freely around it. A high velocity stream of hot air is blasted against the sample until the specimen is dried.

o 1;" ilmted States atent 11 1 1111 5,729,35 Massett 1451 May 1, 1973 [5 SPECIMEN DRYING AIWARATUS 2,608,768 9/1952 Noel .34/224 x 3,327,404 6/1967 Ganier.... ....34/224 X [76] Invent f f Miissett 5261 920,585 5/1909 Lamb ..34 225 glers Drlve, Memphls, Term- 381 16 948,763 2 1910 Hutchins ..34/34 x 3,327,404 6/1967 Ganier ..34/224 X [22] Filed June 1971 2,667,064 1/1954 Andersen et al. ..73/76 [21] Appl. No.: 148,377

Primary Examiner-Carroll B. Dority, Jr. Att Jam s H. Little a e 52 US. Cl .54/225 army 8 p g [51] Int. Cl ....F26b 19/00 57 ABSTRACT [58] Field of Search ..34/22, 34, 35, 219, I

34/225 224; 73/76 For quantitative determination of water in a speclmen of known weight, the specimen is supported in an f oven in a manner that air can circulate freely around [56] Re erences Cited it. A high velocity stream of hot air is blasted against UNITED STATES PATENTS the sample until the specimen is dried.

2,414,642 1/1947 Gary ..34/225 X 1 Claim, 2 Drawing Figures Patented May 1, 1973 3,729,835

l/Il/ v a u waggg 5 INVENTOR FRANKLIN L. MASSETT ATTOR EY FIELD OF INVENTION Measuring and testing, moisture content or absorption characteristic of material, by desiccation or extraction.

PRIOR PATENT ART Dietert US. Pat. No. 2,080,168; Spary U.S. Pat. No. 3,183,710; Christian US. Pat. No. 3,360,985.

BACKGROUND At present there are two principal types of oven construction, the gravity convection oven and the mechanical convection oven. The gravity convection oven depends upon the principle that air rises when heated and settles when cooled. Heaters located at the base of the oven warm the air adjacent to them. The air rises to the top of the oven where it cools and settles to the bottom again. This heating and cooling of the air inside the oven causes the air to remain in motion and accellerates the evaporation of water from the sample. The air movement also helps maintain a more uniform temperature from top to bottom of the oven.

In the mechanical convection oven, this air movement is produced mechanically. The oven is equipped with a fan or blower, producing a uniform air flow and a more uniform temperature inside the oven than can be accomplished by gravity convection. However, the evaporation of water from the sample is not accellerated substantially by the mechanical convection of the air inside the oven. Both gravity convection and mechanical convection ovens require drying a sample for 4 hours to completely remove the water. (Analysis for Water. Methods of Analysis, A.O.A.C., Tenth Edition.)

In addition to oven drying, samples are dried in open atmosphere by hot air blowers or heat guns. However, with this technique, it is difficult to achieve the preciseness of control of all conditions, including temperature and intensity of blast, and uniformity of procedures and results, as is desired for laboratory work.

OBJECTS The object now is to provide for oven drying of specimens which permits analysis of a sample for water in a matter of minutes instead of hours. More particularly, ,it is intended now to provide an oven, the heat of which can be accurately controlled, a sample support within the oven, and an air circulating system whereby a blast of high velocity air strikes the sample at close range, and is thereafter withdrawn from around the sample.

These and other objects will be apparent from the following specification and drawings, in which:

FIG. 1 is a front elevation of an oven with its door open, showing the specimen support therein; and,

FIG. 2 is a side elevation of the oven and air circulating system, the oven being partly broken away to show a specimen on the support.

Referring now to the drawings, in which like reference numerals denote the same element, the oven 2 is of the type ordinarily used for laboratory drying of specimens. It has heat insulating material 4 in its walls,

an insulated door 6, and controls 8 for the electric heating elements, not shown, by means of which the interior.

of the ovencan be accurately controlled. For present purposes, it is sumcient that the atmosphere within the interior of the oven be maintained at a fixed degree within the range of 150 to 200 C. An air inlet 42 and vent 44, discussed hereinafter, are provided.

A specimen support, denoted generally at 10, consists of a funnel-shape enclosure 12 supported on the oven floor by a base plate 14. Across the enclosure, near the top, is affixed a wire mesh screen 16, on the center of which a sample dish 18 is supported. Assuming the funnel to be about six inches in diameter, screen 16 is preferably disposed about one inch below the rim 17 of enclosure 12.

The air circulating system denoted generally at 20 consists of a pipe 22 coupled at 24 to the interior of enclosure 12 well below screen 16. Pipe 22 extends through the rear wall of oven 2, whence it is coupled to a copper tube (not shown) within a heavy rubber hose 26 to the intake fitting 28 of an air or gas pump 30 driven by a motor 32. The delivery fitting 34 of the pump is connected by a copper tube (not shown) within a heavy rubber hose 36 to a pipe 38 which extends through the oven wall and terminates at 40 over the center of enclosure 12 about a quarter of an inch above its rim 17. The direction of air issuing from the pipe terminus 40 is at a 90 angle to the funnel rim. The purpose of the heavy rubber hoses is to provide heat insulation, and limit heat loss from the air circulating system. Pump 30 has a capacity of about 1.4 cubic feet per minute free air flow. The terminus 40 of pipe 38 should be about three-eights inch inner diameter, this providing a calculated velocity of 1,800 feet per minute, or approximately 21 miles per hour. If the air velocity is too great, some types of specimens will be blown about, which is undesirable. Although a desiccant may be placed within the oven, it is preferred to utilize an oven having a fresh air intake 42 and an exhaust port 44. The atmospheric air circulating freely through the oven minimizes the importance of a desiccant. v

In operation, oven 2 is first heated to Centigrade. Then the air pump 30 is turned on and heated air is circulated through the return line 22, through the pump 30 and back through the supply line 36, 38 to the oven chamber for a period of five minutes. This is to preheat the entire drying system. While the system is preheating, a sample to be dried is weighed in a tared moisture dish 18 using an analytical balance. When the system is preheated, the dish 18 containing the sample is placed in the center of the mesh screen in the funnel the oven door 6 closed, and the pump 30 started.

Hot, dry air strikes the sample from 1% inches away at the rate of 1.4 cfm. The air is directed at the center of the funnel. It strikes the sample and is deflected toward the rim 17 of the funnel 12. The air is then drawn down the sides of the funnel and into the return line 22 and back into the pump 30. From there it passes through the supply line 36, 38 and back into the oven where it again strikes the sample. This cycle continues as long as the pump remains in operation. When all the water has been removed from the sample, the pump is shut off, the sample removed from the oven, cooled briefly in a dessicator and reweighed. Loss in weight is reported as water. Drying times for most samples have not as yet been determined. However, the drying time for meat emulsions (raw bologna, raw frankfurters) using this system has been found to be 2 minutes.

This invention provides meat packers with a rapid means of determining the water content of material, such as sausage batters. Since water and protein occur naturally in a fairly constant ratio in meats (3.521),.the protein can be calculated and also the fat (by difference). Water, protein and fat make up 99 percent of the meat components. It is important to the packer to know these values in order to produce a product that is economical, uniform, and that complies with government regulations.

Although only one specimen holder has been disclosed, extra funnel and piping assemblies may be provided to dry a plurality of specimens at one time. Likewise, gas instead of electric heat may be used for the oven, dimensional changes may be made, and the air circulating system may be confined within the oven.

1 claim: 1. Specimen drying apparatus comprising an oven,

means providing a platform for supporting a 

1. Specimen drying apparatus comprising an oven, means providing a platform for supporting a specimen within the oven, an air blast pipe terminating over the platform, an air return pipe leading from below the platform, and pump means for forcing air via said air blast pipe onto said specimen and withdrawing the same via said air return pipe, the means providing a platform comprising a funnel-shape enclosure having the larger end disposed upwardly and means closing the smaller end, and a screen disposed across the enclosure at a distance from the larger end thereof, said air return pipe being connected to the enclosure below said screen. 